BCX-34 (9-(3-pyridylmetayl)-9-deazaguanine is a new purine nucleoside with potential therapeutic value in cutaneous T-cell lymphoma (CTCL). The purpose of this study was to evaluate the pharmacokinetic s and metabolism of radiolabelled (14C) BCX-34 given by intravenous and oral routes with examination of disposition to CTCL skin lesions at specific intervals. Studies in 3 patients demonstrated similar pharmacokinetic patterns with minimal metabolisms (<5%), primarily renal excretion, excellent bioavailability (>80%), and excellent delivery to skin. This study forms the basis for planned phase I study of BCX-34.